This invention relates to an integral liquid pump and drainback valve intended for use in pumping popcorn popping oil from a storage container to a popcorn popping kettle. In the production of large quantities of popped popcorn, popcorn popping oil is a critical ingredient which must be delivered in a predetermined quantity, along with the corn to be popped, to the popping kettle at the beginning of a popping cycle.
This need has been met in the past by dispensing popcorn popping oil from a steel pail. A pump for pumping the oil to the popping kettle is placed in the pail through the open top of the pail. In the mass production of large quantities of popcorn, a series of independent poppers may be operated simultaneously with the popcorn popping oil being delivered by the pump to each of the plurality of poppers as they begin their respective cycles. In such a popping operation, a large quantity of popping oil must be readily available.
To better meet these needs, an improved storage and metering apparatus for popcorn popping oil has recently been invented by the applicant for this patent. The improved storage and dispensing means includes a housing having inclined shelves upon which are placed rectangular boxes containing plastic bags filled with popcorn popping oil. The shelves support the boxes in a tilted position such that a dispensing connection provided at the bottom of the plastic bag, which may be extended through the box, is in a lowermost position such that all of the popcorn popping oil may be drained through the dispensing connection from the bag. The shelves are provided with thermostatically controlled electrical heaters so as to maintain the popcorn popping oil at a desired viscosity. A pump is provided for withdrawing the popcorn popping oil from the bags and supply it to a popping kettle located at a higher elevation than the bags. This improved storage and metering apparatus for popcorn popping oil is set forth in U.S. patent application Ser. No. 07/984,063, filed Nov. 30, 1992 by the applicant and is assigned to C. Cretors & Company. The disclosure of the cited application, which issued on Apr. 12, 1994 as U.S. Pat. No. 5,301,601, is incorporated herein by reference.
As set forth in the cited patent application, the popcorn popping oil storage containers are mounted below the elevation at which the popcorn popping oil is supplied to the popping kettle. An elongated pipe or tubing is provided to deliver the popcorn popping oil from the pump discharge outlet to the popping kettle. Since popcorn popping oil may solidify at room temperatures, it is desirable that the popcorn popping oil not remain in the entire length of the pipe or tubing such that, upon cooling to room temperature, it would prevent or make much more difficult further pumping of the popcorn oil. To eliminate this problem, as disclosed in the above-mentioned patent application, a bypass path is provided between the inlet and discharge ports of the pump to permit the popcorn popping oil to drain back through the discharge pipe or tubing from the popcorn popping kettle to the supply container. When the pump is de-energized, a solenoid valve in the bypass path is energized and thereby opened to permit flow through the bypass path. Since the popcorn popping oil will flow back into the supply container until the level of the popcorn popping oil in the discharge line is equal to-the level of the oil in the container, considerably less popcorn popping oil remains in the discharge tubing or pipe to harden, or at least become more viscous.
The provision of the drainback path as disclosed in the cited patent application require installation of not only the solenoid valve, but also a bypass fluid flow path in which to connect the solenoid valve. Electronic circuitry to control the energization of the solenoid valve is also required. Further, the bypass path itself provides a further flow path in which the popcorn popping oil may solidify if not heated. Thus, it would be desirable to provide a drainback arrangement without the requirement of providing piping or tubing for a separate path, and an electrically operated solenoid valve and related electronic control circuitry.